Hi Guys,

So...I've finally reached the point of putting the fuel system back on the engine after a refresh and have run into a question. Two of the passenger side intake nuts on my 2.0 (the left and right ones) torqued up to 14lbs fine. The center nut stopped getting tighter at about 8lbs. I assume that the stud is spinning in the head. Would you leave well enough alone and trust that the seal will be fine at 8lbs...or would you pull it apart and deal with the center stud?

I def don't want to put the engine back and then find a vacuum leak...but I also don't want to make a bigger problem where may not be one in the first place.

Thoughts?

Fix it, with either an oversize stud on the head side or a thread insert

I wouldn't leave it sounds like the threads are striping out of the head. Will cause problems for sure later. Maybe drill head for step stud or repair with threaded insert.

Brett

Drill it out and use a Helicoil or Timecert. The general opinion is that Timecert's are better than Helicoil's. I used a Helicoil to repair mine in 2010 and it's still in and working fine. Don't be afraid to drill it out free hand. Here is the trick; step drill. IIRC, I used 3 or 4 bits, increasing the size ever so slightly with each bit. This guarantees that each pass is self centering, unless you get Ham fisted with it. Use a drill stop because when using this method in aluminum the bits want to grab and pull thru quickly.

Definitely fix it. Heli-coils are fine in this application. But make sure you have 1 bolt diameter worth of thread engagement at minimum. 1.5 is ideal

Helicoil it. Only takes a minute now and saves you from doing it when it's in the car.

Ian,

Hit me up if you want to barrow the tools. I bought the setup to replace the studs on my 2.0 heads after having 3 of the 4 strip. Did it with the engine still in the car, then of course a valve dropped so all the work was for nothing
Anyway I still have helicoils and the tool. OR you can get them off amazon, that's what I did.

Thanks guys.

It seems the threads have indeed stripped out. At least running a die on the stud cleaned it up and it can be reused. Bummer seeing the aluminum shavings.

I ordered an M8 1.25 helical kit from amazon. Thanks, Nditiz for the loaner offer...I just figured this is probably something I should have in the toolbox and its pretty inexpensive.

Kent– thanks for the tips. Will try the step drill method. I wish there was a way to use a small hand press, but there isn't enough flat area. Any other tricks welcome. The prospect of taking a drill to the head is as scary as it sounds!

How does this happen anyway? Over-torqueing?

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It's not that bad Ian, engine out, you're looking down at your work, and it only takes a little patience. Much easier than drilling out an exhaust stud under the car...

you would definetly know, joe

I've done it from under the car and it wasn't difficult at all.
With the engine out it would be even easier.
just go SLOW.

Seeing as how the threads were completely stripped away, it might be possible that no additional drilling is required. Clean the hole out and try a fit check of the new heli-coil tap in the hole. You may be able to just start tapping.

Nope, drill it correct size, do it right, a broken off tap will ruin your day.

The hole 'might' be the correct size, but it must be checked and drilled if it is not.

One has to be doing a lot of things wrong to achieve a broken tap on cast aluminum. But I am certain there are peeps who will find a way.

Depends on the tap and the depth and the hole diameter. You could break off a tap in jello given the right circumstances.

Yes, as I have mentioned there are very talented peeps out there.

The reason I mentioned it 'might' already be out to heli-coil tap drill size, is because the material removed by the OE stud was up to the full 'major diameter'. The Heli-coil drill size for this application is right about 8.3mm Dia. which is approx. 0.0118" (inches) larger than the stud's major diameter.

But yes, ABSOLUTELY take the high road and do this the RIGHT way. Drill the cast aluminum to 8.3mm, vacuum all debris then begin tapping with the CORRECT Heli-Coil tap. Using a lot of tapping lube and being very careful not to break the tap in the hole. Because we all know this can happen, even in jello.

I love time-cert and have a set for all the 901/915/930 stud sizes, which includes 8x 1.25. I even have the over sizes of this for those "oh shit" moments. If you get stuck with the bore being too big for the helicoil, hit me up and I can lend you some time-certs.

I knew the jello salad would get attention. And yes, I can screw up a sure thing.

Thanks everyone. I got a helicoil kit and the recommended drill bit. My plan is to do as Kent suggested and enlarge the hole to the correct size using several passes of progressively larger bits. With a stop just longer than the helicoil itself.

I notice that the hole is approx 1 inch deep, but the helicoil should only go about half that depth in (so that its threads begin just below the opening). I assume that the "ridge" which will be created by the drill bit(s) will be a substantial enough "seat" for the helicoil, correct? I read somewhere that it needs to bottom out. Or does it? This is my first experience with them.

Thanks, Doc for offering up the timecerts if I sh*t the bed. I should be able to get to this project on Monday. Right after I whip up a batch of Jell-o. Will report back...

Before drilling be sure to put tape over the intake ports. It would be best to use a 'drill stop' to control the depth of the drill. But seeing as how opened up the hole is ... you should be able to 'sense' when to get to the bottom (in the form of additional resistance). I would not push very hard, just be sure to hold the drill straight or use a 'drill block'.

Once you tap the hole with the heli-coil tap. Clear the chips and as an option you can add some blue Loctite to hold the heli-coil in place once installed. The heli-coil should be about 1 thread below the surface before you break the tang. This will help prevent the coil from being dislodged and will also keep the coil threads in good alignment to start your stud. I guess you can add Loctite to the stud as well.